<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        function randomString(n){
            let ans = "";
            for(let i = 0;i < n;++i){
                let asi = Math.floor(Math.random()*129);
                ans += getLetter(asi);
            }
            console.log(ans);
        }
        function getLetter(asi){ // 把指定的Unicode转换成字符串
            return String.fromCharCode(asi);
        }
        randomString(3);
    </script>
</body>
</html>